It's still slightly nose heavy. My gas tank is pretty close to the CG - how about yours? I know on a lot of planes they're forward of the CG. Those, if I understand correctly, should be balanced with an empty tank, just a little heavy on the nose.

Thanks grosbeak for the comeback. sounds like we are kinda on the same page. My Pulse 60 with the Saito 100 came out just a little tail heavy. I think because i purchased a Turbo Header Muffler from RC Specialties and it is not as heavy as the Saito Muffler. I ended up adding about 4oz. on the firewall just under the motor mount to get it just a touch nose heavy with an empty fuel tank. I also never did like balancing a plane on dowel sticks under the wing, so on all of my planes I find the CG and run a small piece of control tubing through the plane from the bottom to the top. That way I can hang it on a string. (heavy fishing line) and check the balance fwd and aft and also the lateral balance. I've always had very good luck doing it that way. I post some pics in a few days.

Another problem I need to fix on the ARF Pulse is the wing and the horizontal stab are not on the same plane. I need to take the rear stab off and cut or sand one side of the fuse to get one side of the stab lower so to be on the same plane as the wing. If I cannot get it corrected I may contact Hanger 9 or Horizon and see if they will replace the fuse. I hate to have to do that though because of all the time I have invested in just getting it this far towards the first test flight. How much will it effect the flying of the plane if the wing and the hor stab are not in a straight line or parallel with each other when when viewed from the front or rear of the aircraft??

Another problem I need to fix on the ARF Pulse is the wing and the horizontal stab are not on the same plane. I need to take the rear stab off and cut or sand one side of the fuse to get one side of the stab lower so to be on the same plane as the wing. If I cannot get it corrected I may contact Hanger 9 or Horizon and see if they will replace the fuse. I hate to have to do that though because of all the time I have invested in just getting it this far towards the first test flight. How much will it effect the flying of the plane if the wing and the hor stab are not in a straight line or parallel with each other when when viewed from the front or rear of the aircraft??

Stokey

I'm no expert but it can't be a good thing - at the very least I expect it wouldn't climb or descend in a straight line. Here are a couple of simple diagrams - for the sake of the discussion let's assume everything else about the airplane is perfectly balanced and trimmed.

Wing and horizontal stabilizer in the same plane:

With up elevator, the plane pitches straight up.

Wing and horizontal stabilizer not in the same plane:

With up elevator the plane still pitches up but there is some degree of ruddering, causing the plane to yaw towards the lower side of the horizontal stabilizer.

I'm using reason here, not experience. I hope someone with more of the former and/or the latter will chime in. If not, there may be a better forum topic for this question, like Questions and Answers.

I lost a elevator servo on my Pluse 60-resulted in a crash that riped out the L/G and broke the fusalage in half behind the wing saddle. When I glued her back together the fuss had a slight twist resulting in the same problem. Since the tail is bolt on, I shimmed the low side aprox 1/32 until the horizontal stab was level. Easy Fix.

Thank you for the input Guys!
I was thinking along the same lines, but wanted to get some other ideas. A friend and myself were looking at the plane the other night and both thought that shimming the tail section would be the easiest fix, although reluctant to do that without asking some questions first. I'll probably give that a try this evening after finishing up the "honey-do" chores today. Have a great Day and thanks again for your thoughts.
stokey

You might also try twisting the fuss in the direction need'ed to level the stab, and re-shrink the covering that loosens, to hold it in place. A helper would be benaficial. Use a shim to correct the last bit of miss-allighment. I'd say you'll be fine & wont even be noticeable when the plane is done.

I have been following this post with interest. (Ever since my first Pulse died an ugly death when the elevator broke loose.) Anyway's Horizon's free replacement with the new elevator has been great. I've been flying it for about a year now. This is only my third plane but have noticed something that I hadn't before.

As the plane is flying level (1/2 throttle) and then when I hit the throttle the plane tends to pitch up slightly and rolls to the right. I have a Saito 115, 15x6 prop. The plane balances to spec but I would note this. Lateral balance is a bit off. If I put 1.5 grams of lead on the outermost part of the left wing (viewed from behind) it now balances level. Could this little amount of weight make that kind of difference? Or, is something else up? Viewing the plane there appears to be no warping etc. Thank you.

While building my Pulse 60 I hung the plane from a string through the recommended balance point. I have a Saito 100 on it , so had to add about 3/4 to 1 oz. on the firewall to get the balance a touch nose heavy. When viewing from the rear, I noticed the left wing dipped about 1" , so plan to ad just enough weight to the right wing to bring to level lateral. sounds like this is the same problem as you are describing.
Stokey

Put the DLE 20 in today with a Sullivan Mount and noticed I won't be able to get to the high/low speed adjustment needles - oh well, I'll just have to tinker with that later. Do have a question about the choke and throttle arrangements - how'd you guys link those up?

Even got the engine centered......well almost. Too bad the cowl had to be cut up so badly for the muffler

The rear exhaust Syssa has been around a while, but other 30cc manf.'s seem to be catching on to the fact there's a big demand for REAR EXHAUST OUTLETS!! Doesn't seem to be that big a deal regarding design or manufacturing on those, hopefully it won't take too long for the 20cc manf's to figure out the same thing? Then we won't have to hack up our cowls like this.

Agree though, very nice job on the necessary evil! Actually, I saw one muffler exposed like this that had been painted to match, didn't look to bad at all! No clue how that would hold up after extended service though.

Put the DLE 20 in today with a Sullivan Mount and noticed I won't be able to get to the high/low speed adjustment needles - oh well, I'll just have to tinker with that later. Do have a question about the choke and throttle arrangements - how'd you guys link those up?

Hi Jerry
Yup just moving slower every day. My Pulse 125 is still an old rocket ship and I'm still enjoying it to the max. keeps my fun meter pegged when I take it out. I used the compact wrap around muffler and was able to cut much less of the cowl than you had to. I got no notice from this thread as I normally do. Take Care. Brian

Quote:

ORIGINAL: tailskid

Even got the engine centered......well almost. Too bad the cowl had to be cut up so badly for the muffler

I acquired a Pulse 125 at the annual local RC club auction two years ago. It came from the estate of a deceased club member. He had it powered with a OS 120AX and standard issue muffler. It's been sitting on the shelf in "moth balls" until a couple weeks ago when I pulled it out and dusted it off and began readying it for flight. I choose to mount up a Saito 125, and installed a larger fuel tank. I swapped the standard wheels (had flat spots from sitting) with new Sullivan Skylites, and added a new Sig medium size tail wheel assembly. I changed out the battery with a Hobbico 1800mah LiFe battery, just behind the fuel tank. I rounded it out with a used 2 3/4" Tru Turn spinner.

I expected to have to add a bit of weight to the front of the airplane when I balanced it, but... I didn't expect to need 12 ONCES of lead up near the firewall. The CG is supposed to be 3 11/16" aft of the leading edge of the wing. I've tried it right side up and inverted, doesn't make any difference, it's going to take at least 12 onces. Has anybody else run into this particular problem...? I'm going to move the battery farther forward, and I may install a 2100 mah battery to offset some of the lead. But still, this seems like I'm adding a lot of weight. Is this consistent with other folks experiences?

I acquired a Pulse 125 at the annual local RC club auction two years ago. It came from the estate of a deceased club member. He had it powered with a OS 120AX and standard issue muffler. It's been sitting on the shelf in ''moth balls'' until a couple weeks ago when I pulled it out and dusted it off and began readying it for flight. I choose to mount up a Saito 125, and installed a larger fuel tank. I swapped the standard wheels (had flat spots from sitting) with new Sullivan Skylites, and added a new Sig medium size tail wheel assembly. I changed out the battery with a Hobbico 1800mah LiFe battery, just behind the fuel tank. I rounded it out with a used 2 3/4'' Tru Turn spinner.

I expected to have to add a bit of weight to the front of the airplane when I balanced it, but... I didn't expect to need 12 ONCES of lead up near the firewall. The CG is supposed to be 3 11/16'' aft of the leading edge of the wing. I've tried it right side up and inverted, doesn't make any difference, it's going to take at least 12 onces. Has anybody else run into this particular problem...? I'm going to move the battery farther forward, and I may install a 2100 mah battery to offset some of the lead. But still, this seems like I'm adding a lot of weight. Is this consistent with other folks experiences?

Jerry Hicks

Hey Jerry the OS 120AX is a PEACH! for me for this model, concidering I also have a NIB Saito 125 on the bench. I added no weight to get the CG dialed in to spec's using the Hangar 9 aluminum engine mount. Only added 1/2 ounce to balance it laterally. I also have my battery (JR 2700mah) mounted just behind the fuel tank. Hmm ya 12ounce seems like much, if that much weight is needed you might want to try a better but heavier engine mount instead of the stock one. Like the Hangar 9 aluminum one I'm using, you might only have to add like 7 ounces, or maybe even that heavy $40 metal Sullivan engine mount which might put you right on. Just trying to give you somtin to bit on.

Thanks for the info, much appreciated. I just pulled the battery and the tank and I'm reinstalling them as far forward as I can in the forward compartment. That should help some. I used a Great Planes 120 size mount, it was a bit heavier than the Hangar 9 mount that it replaced. I'm guessing that the heavier Sig medium size tail wheel assembly is part of the problem. The Hangar 9 tailwheel arrangement is connected directly to the rudder....makes it hard on the rudder servo. This is a fairly stout aluminum leaf tailwheel, and it doesn't take much weight that far back to make a big difference on the balance....

Yes Jerry that tail wheel setup is the nemesis, well then that explains it. Well it looks like you'll have pile on some weight. Hmm I wonder what that Sullivan tail wheel setup weighs compared to the Sig?

Thanks to this thread I've got this model coming. Horizon was out so I ended up ordering from Espirit Models. Hoping it's not the older version. I placed my first order from Troy built models. I thought they were willing to go the extra mile to discuss things before ordering. I'd like to know which muffler to use? TBM came up with a silencer for the stock muffler which they include with an engine purchase (new plug too) . There's a video on their site demonstrating it. What do I need to do for engine cooling? No spinner? Do I need to replace the main gear and tailwheel?